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re: [midatlanticretro] Re: Using 2SIO to download BASIC into an Alair without a disk drive or cassette.

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  • Bob Applegate
    ... Whoa! Run a real memory test! I m assuming the memory is static, but there are lots of different kinds of tests that look for refresh problems on dynamic
    Message 1 of 15 , Feb 26, 2010
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      Bill Degnan <billdeg@...> wrote :


      > I am not using a terminator.
      > My memory tests so far have all been manual read/write/read tests at each
      > page location 0000, 1000 - F000. I have swapped RAM cards into a number of
      > configurations, and I usually get the same result. It's possible that my
      > laptop serial port is not right? Not sure yet.
      > cd

      Whoa! Run a real memory test! I'm assuming the memory is static, but there are lots of different kinds of tests that look for refresh problems on dynamic memory, as well as shorted address/data bits, bad bits in chips, etc. You wouldn't believe how many memory problems slip through because of tests that don't run sufficiently complex algorithms.

      I'd also test one board at a time, or at least pull boards you don't need. You've got four 16K boards, right? Pull all but one and check the portion not used by the test code. Once it seems to work, put in another board and test all 16K of it using a really good (extensive) memory test. Now you've got a "golden board" that is known, or at least presumed, to be good.

      Bob


      ___________________________________
      NOCC, http://nocc.sourceforge.net
    • Bill Degnan
      ... each ... number of ... my ... there are lots of different kinds of tests that look for refresh problems on dynamic memory, as well as shorted address/data
      Message 2 of 15 , Feb 26, 2010
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        >
        >
        > > I am not using a terminator.
        > > My memory tests so far have all been manual read/write/read tests at
        each
        > > page location 0000, 1000 - F000. I have swapped RAM cards into a
        number of
        > > configurations, and I usually get the same result. It's possible that
        my
        > > laptop serial port is not right? Not sure yet.
        > > cd
        >
        > Whoa! Run a real memory test! I'm assuming the memory is static, but
        there are lots of different kinds of tests that look for refresh problems
        on dynamic memory, as well as shorted address/data bits, bad bits in chips,
        etc. You wouldn't believe how many memory problems slip through because of
        tests that don't run sufficiently complex algorithms.
        >
        > I'd also test one board at a time, or at least pull boards you don't
        need. You've got four 16K boards, right? Pull all but one and check the
        portion not used by the test code. Once it seems to work, put in another
        board and test all 16K of it using a really good (extensive) memory test.
        Now you've got a "golden board" that is known, or at least presumed, to be
        good.
        >

        Agreed, but I am trying to get programs into the system - chicken and egg
        problem here. I will test the RAM using a system that can already load
        programs.

        Bill
      • Bob Applegate
        ... Maybe I missed something but the subject implies you re loading a BASIC interpreter. That s much larger than a memory test and it won t test memory. Use
        Message 3 of 15 , Feb 26, 2010
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          Bill Degnan <billdeg@...> wrote :


          > Agreed, but I am trying to get programs into the system - chicken and egg
          > problem here. I will test the RAM using a system that can already load
          > programs.

          Maybe I missed something but the subject implies you're loading a BASIC interpreter. That's much larger than a memory test and it won't test memory. Use a smaller program that can test your hardware before trying to load something larger.

          You're still using unknown RAM, but a memory test is a lot smaller and will use less unknown RAM to run.

          The other thing is that I seem to remember your failure happened at a page boundary. How big are the RAM chips and what was the address again? Maybe it happened on a chip boundary.




          ___________________________________
          NOCC, http://nocc.sourceforge.net
        • Bob Applegate
          ... If the hex address ends in 00 then it s a page boundary. What was the address where it failed and what type of RAM chips are on the boards?
          Message 4 of 15 , Feb 26, 2010
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            Bill Degnan <billdeg@...> wrote :


            > I can't tell if it's a page boundary or not.

            If the hex address ends in 00 then it's a page boundary. What was the address where it failed and what type of RAM chips are on the boards?


            ___________________________________
            NOCC, http://nocc.sourceforge.net
          • Bill Degnan
            ... interpreter. That s much larger than a memory test and it won t test memory. Use a smaller program that can test your hardware before trying to load
            Message 5 of 15 , Feb 26, 2010
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              >
              > Maybe I missed something but the subject implies you're loading a BASIC
              interpreter. That's much larger than a memory test and it won't test
              memory. Use a smaller program that can test your hardware before trying to
              load something larger.
              >
              > You're still using unknown RAM, but a memory test is a lot smaller and
              will use less unknown RAM to run.
              >
              > The other thing is that I seem to remember your failure happened at a
              page boundary. How big are the RAM chips and what was the address again?
              Maybe it happened on a chip boundary.
              >

              I can't tell if it's a page boundary or not.

              I am working through this web site:
              http://www.solivant.com/altair_bootloaders/index.php?album=altair_bootloader
              s&pagen=1

              I will keep at it. I have followed every page closely including the
              troubleshooting section.

              Bill
            • Dan Roganti
              ... Anytime you add more loads on that bus, by adding more cards, it s wise to use a terminator card. The signal quality begins to degrade by the consequence
              Message 6 of 15 , Feb 26, 2010
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                Bill Degnan wrote:
                > I am not using a terminator.
                > My memory tests so far have all been manual read/write/read tests at each
                > page location 0000, 1000 - F000. I have swapped RAM cards into a number of
                > configurations, and I usually get the same result. It's possible that my
                > laptop serial port is not right? Not sure yet.
                >

                Anytime you add more loads on that bus, by adding more cards, it's wise
                to use a terminator card. The signal quality begins to degrade by the
                consequence of electrical reflections between all the drivers from more
                cards on the bus.

                I uploaded some memory tests that I found online to here. One of them is
                short that you can thumb-in. It's in assembly still, it's not a
                comprehensive test but it's a start, under folder S-100 Test Code.

                =Dan
              • Bill Degnan
                I will take a look. I may not have a terminator that works. I have to check bd ... Alair without a disk drive or cassette. ... each ... number of ... my
                Message 7 of 15 , Feb 26, 2010
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                  I will take a look. I may not have a terminator that works. I have to
                  check
                  bd

                  -------- Original Message --------
                  > From: "Dan Roganti" <ragooman@...>
                  > Sent: Friday, February 26, 2010 2:24 PM
                  > To: midatlanticretro@yahoogroups.com
                  > Subject: Re: [midatlanticretro] Re: Using 2SIO to download BASIC into an
                  Alair without a disk drive or cassette.
                  >
                  > Bill Degnan wrote:
                  > > I am not using a terminator.
                  > > My memory tests so far have all been manual read/write/read tests at
                  each
                  > > page location 0000, 1000 - F000. I have swapped RAM cards into a
                  number of
                  > > configurations, and I usually get the same result. It's possible that
                  my
                  > > laptop serial port is not right? Not sure yet.
                  > >
                  >
                  > Anytime you add more loads on that bus, by adding more cards, it's wise
                  > to use a terminator card. The signal quality begins to degrade by the
                  > consequence of electrical reflections between all the drivers from more
                  > cards on the bus.
                  >
                  > I uploaded some memory tests that I found online to here. One of them is

                  > short that you can thumb-in. It's in assembly still, it's not a
                  > comprehensive test but it's a start, under folder S-100 Test Code.
                  >
                  > =Dan
                  >
                  >
                  >
                  >
                  >
                  >
                  > ------------------------------------
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